Field
This disclosure relates generally to circuits, and more specifically, to a substrate bias circuit and method for biasing a substrate.
Related Art
In integrated circuits that have CMOS (complementary metal oxide semiconductor) transistors, a body, or well, terminal of the P-channel transistors is typically connected to a positive supply and the body terminal of the N-channel transistors is typically connected to ground. In some CMOS circuits a technique called reverse back biasing may be used to change transistor threshold voltages to reduce leakage current and thus reduce power consumption. However, during power-up of an integrated circuit configured to provide reverse back biasing, if the well bias is applied after the power supply voltage is applied, a condition may exist that creates an undesirable current path through series-connected N-channel and P-channel transistors. The condition may lead to excessive current consumption, and in high temperature cases, may result in latch-up of the integrated circuit.
Therefore, a need exists to prevent excessive current and possibly latch-up in an integrated circuit during power-up.